Influence

I like to put Infulence starbases near enemy planets, but the AI seems to take it as a slap in the face, and I would probably not get away with it on higher difficulty levels. Basically, if you put them near enemy planets, you'l' begin to subvert them, and if you put them near your planets, you'll protect them from being subverted themselves. I think.
Either way, make sure you keep it upgraded. It won't do much until you get subversion centers or better. Then the real fun begins! (This is a total greenhorn speaking by the way, so I may be completely wrong!)

I'll leave the formula and all the technicalities to the nerds of greater intelligence.

The manual isn't clear on a lot of things.

Every starbase provides a zone of influence, but it is pretty weak. Influence starbases have the ability to improve the influence in their area of effect. So, when you have an influence starbase with the full set of cultural dominance features on it and it has a 300+% influence bonus on it, it is taking whatever influence of yours is in the area of effect (its own, if no other planets are nearby) and upping it by 300%.

That is why, generally, having one influence starbase isn't enough to cause a planet (of decent size) to revolt. However, employing 2 is; they both cast a weak influence radius, but the simultaneous multiplication of both rapidly overwhelms just about everything. Taking an influence of 10 and multiplying it times 4 is only 40. Taking an influence of 20 (doubled because of 2 starbases) and multiplying it by 8 is 160, which is pretty overwhelming.

Note that the above numbers are not factual numbers. The game doesn't say what the base influence of a starbase is.

So the starbase does not exert its own influence.. it's just a multiplier.

In that case, can we make any assumptions about how you establish how much influence you are exerting on any piece of space? Is it a function of distance from a centre of influence?

I wish there was some more specificity on this, as it seems pretty central to understanding how to use these bases.

I see a third use for influence bases: to extend your boundaries into space (not necessaily subverting a planet) to increase your tourism revenue.

I'm wondering if it's possible to make a civ's only colony rebel thus eliminating them. I wonder because I was playing a game last night where I was dominating the board and I had a small civ stuck on one planet deep within my influence. The influence I was exerting was something like 25x theirs , but turn after turn they would not revolt. So I reiterate, will a planet that is a civ's only stronghold be impervious to a revolt?

Yes, you can flip the last planet of a civ. They will even say it it the last planet in the flip notification. You cannot, however, flip a 'minor race' planet with culture at all.. So my guess is that was the planet you saw.

No, this planet belong to the Yor collective; this is odd, I don't know what happened. Odd...

Don't evil civs get a planetary improvement that prevents culture flips?

the yor have +100 loyalty maybe more with other bonuses during the game so that could have had sumthing to do with it, also if the planet had a high population..?

There is one Galatic wonder which prevents defections